A Wideband and High-Gain Filtering Antenna for 5G Millimeter-Wave Applications

A wideband and high-gain millimeter-wave (mm-wave) filtering antenna is proposed for 5G applications. The antenna mainly consists of a substrate-integrated waveguide (SIW) cavity with a rectangular slot, four identical rectangular patches with metallic vias, and a parasitic strip. Due to the perturbation of the slot, the SIW cavity is able to generate two resonant modes in the passband and simultaneously a radiation null at the lower bandedge. The via-loaded patch can generate an additional resonant mode to increase the operating bandwidth and further enhance the in-band gain of the antenna. In addition, the parasitic strip can offer the fourth resonance in the passband and, in the meantime, generate another radiation null at the upper bandedge due to its interaction with the rectangular patches. Consequently, a quasi-elliptic bandpass filtering response is achieved, along with enhanced impedance bandwidth and boresight gain. For demonstration, a prototype operating in the 5G mm-wave band is fabricated and measured. The prototype shows an impedance bandwidth of 18.4%, an average gain of 10.1 dBi, and an out-of-band suppression level of about 20 dB in the stopbands.